Allot



Patented Apr. 30, 1935 UNITED. STATES ALLOY Edward A. Capillon,

Baker & Company,

Attleboro. Mass. 'erlc E. Carter, Maplewood, N. 1., Inc., Newark,

poration of New Jersey No Drawing.- Original application April 25, 1984,a

Serial No. 722,316. tion July 4 Claims.

This application is a division of our copending application Serial No.722,316 and, the invention relates in general to alloys and moreparticularly to an alloy to be used for the manufacture of 5 watchcases, optical frames, jewelry, dental appliances and metal parts ofdentures, electrical switch contacts and conductors and the like; andthe alloy may be used either alone or as a substitute for the goldalloys at present used in the manufacture of gold-filled or rolled goldplate articles.

One object of the invention is to provide an alloy containing a majorportion of precious metals other than gold which shall be at least theequal of the gold alloys heretofore generally used in many propertiesand the superior of such gold alloys in other properties orcharacteristics for the purpose specified, and at the same time can beproduced at less cost than the usual gold aloys.

Another object of the invention is toprovide an alloy which shall beless subject to tarnish and more resistant to attack by nitric acid thangold alloys, and which shall be sufiiciently soft to permit easy workingwithout undue damage to tools and dies, and yet shall be hard enough towithstand wear and have some resiliency or springiness which isespecially desirable in optical frames and jewelr Other objects andadvantages of the invention will appear from the following description.

We have discovered that for the purpose described, useful alloys can beproduced by combining palladium, platinum, silver, and a base metal, forexample, a metal of the iron group, or copper, when palladiumconstitutes at least thirty per cent of the alloy. Palladium has a muchlower specific gravity than gold, is less expensive and at the same timehas better resistance to tarnishing and acid attack than the usual goldalloys; but palladium alone is too soft to withstand the wear incidentto use in optical frames, jewelry and'watch cases. The combining ofsilver with the palladium in part compensates this softness of palladiumand makes the alloy harder, although the alloy is much softer than, forexample, white gold. Moreover, silver is relatively inexpensive whichaids in producing the alloy at low cost. While silver has relativelyless resistance than gold alloys to tarnish and acid attack, thepalladium in the alloy greatly reduces the tendency to'tarnishing of thesilver. Greater degree of hardness to provide a certain degree ofspringiness in the alloy and without material in- Div] 10, 1934, SerialNo. 734,507

ded and this applicacrease in cost, which is desirable in optical framesand jewelry, is obtained by adding a relatively inexpensive base metal,for example, nickel, iron, cobalt or copper. The alloys have a finewhitish in quality excels the color of white gold.

The aforesaid alloy consisting of palladium silver and the base metal,has a high degree of resistance to tarnish'andacid attack, but theresistance is not complete. In many cases complete resistance tocorrosion is highly desirable, and while working to accomplish thisresult, we discovered that the addition to the other metals of arelatively small amount of platinum'gives the unexpected effect ofrendering the alloy practically completely resistant to tarnish and acidattack. Platinum is at the present time only slightly more costly thangold, and thus this remarkable efiect of such a small amount ofplatinum, is obtained at only a slight increase in cost, which isimportant where it is desired to provide an alloy at about the same orlower cost than the usual gold alloys.

We have found that these metals can be combined in differenceproportions to produce satisfactory alloys. Good alloys may contain fromthirty-five to seventy percent of palladium and platinum of which themajor portion is palladium, the remainder of the alloy being silver, anda base metal with the amount of silver several times greater than theamount of base metal. The preferred alloy consists of about forty toforty-five percent of palladium, about five to ten percent of platinum,about forty-five percent of silver, and about five percent of basemetal, for example, nickel, iron, cobalt or copper.

In all cases it is an important feature of the alloy that the smallamount -of platinum very remarkably and unexpectedly increases theresistance of the alloy to tarnish and acid attack, and the greatsignificance of this feature is emphasized when the relatively lowresistance of the other component metals of the alloy to tarnish andacid attack, is remembered.

The alloy is less subject to tarnish and attack by'acids than the usualgold alloys. It has a lower specific gravity than gold and because ofthis and the lower cost of the metals, the alloy is less expensive thanan alloy having a percentage of gold by weight equal to that of thepercentage of the palladium and platinum in our alloy. The alloy issofter than white gold alloys and can be more easily worked, and yet issufficiently hard to withstand wear and has mainder oi the alloy beingsflver and about five percent oi nickel. A

3. An alloy consisting of iromforty to fortyfive percent of palladium,from five to ten percent of platinum, about forty-five percent ofsilver, and about five percent of nickel.

4. An alloy consisting 01.1mm thirty-five percent to seventy percent ofpalladium and platinum of which five to ten percent is platinum, the

remainder of the alloy being silver and about five 10 percent or a metalof the nickel group.

. EDWARD A. CAPILLON.

FREDERIC E. CARTER.

